Authentication failed
- Confirm the username format required by the provider; many services require the full email address.
- Replace the stored password if it was rotated or copied before the provider displayed its final value.
- Confirm SMTP AUTH is permitted for the mailbox or application. Some providers require an app password or OAuth-based relay instead of the normal account password.
TLS or connection failed
- Match port 587 with STARTTLS or port 465 with SSL/TLS unless the provider documents another combination.
- Confirm the hostname is the provider’s SMTP hostname, not its webmail address.
- Ask the provider or network administrator whether the server allows connections from the DMTG Tech service.
Sender rejected or relay denied
- Use a From address the authenticated account is allowed to send as.
- If the organization uses a connector or relay, confirm its accepted domains and source restrictions.
- Check SPF, DKIM, and DMARC alignment with the organization’s email administrator.
The test says sent but no message arrived
- Check spam, quarantine, transport rules, and the provider’s message trace.
- Test a mailbox in the sender’s own organization and a separate external mailbox.
- Allow a few minutes before repeating a test; repeated identical messages may be grouped or rate-limited.